Renewable fuse



March 23, 1937. L. A. KAUFFMAN RENEWABLE FUSE Original Filed April 24, 1955 Patented Mar. 23, 1937 I( UNITED STATES PATENT OFFICE RENEWABLE FUSE Application April 24,

1935, Serial No. 18,039

Renewed February 6, 1937 2 Claims.,

The present invention relates to indicating fuses and more particularly to a plug fuse employing renewable fuse elements having amongst its principal desiderata the provision of a casing for such plug fuses, having a removable section in which the fusible element may be detachably arranged in order that when such iusible element becomes blownvor ruptured, a new element may be easily and readily substituted therefor without causing the entire fuse plug being discarded.

Another desideratum of the invention is to provide a sectional casing for fuse plugs having an indicator connected in series with the terminals of the fuse, a fusible element housed within the casing and electrically connected to the terminals of the fuse, a detachable connection between the sections of the casing whereby access may be readily gained to the fusible element therein for renewing the same when it becomes blown or ruptured and all of the various parts of this fuse capable of being easily assembled without the aid of special tools thereby n materially reducing the cost of manufacturing the same.

A still further object of the present invention is to provide a fusible element and holder therefor which will be comparatively inexpensive in the cost of.v manufacture, easily and readily handled and capable of being placed within a fuse casing to establish an electrical connection between the terminals of the fuse.

A still further object of the invention is to provide a holder capable of retaining a series of fusible elements and which holder may be easily and readily inserted within the casing of the fuse whereby any one of the fusible elements carried by such holder may be utilized for establishing an electrical connection-between the terminals of the fuse.

Other objects of the invention will be in part obvious and in part pointed out hereinafter.

In order that theinvention and its mode of operation may be readily understood by persons skilled in the art, I have in the accompanying illustrative drawing and in the detailed following description based thereon, set out one possible embodiment of the same.

Figure 1 is a vertical section through the fuse embodying the present invention;

Figure 2 is a .horizontal section taken on the line 2--2 of Figure 1 in the direction of the arrow points;

Figure 3 is another horizontal section taken (Cl. 20G-125) yon the line 3-3 oi Figure l in the direction of the arrow points, and

Figure 4 is a plan view of the holder with the fusible elements,Y mounted thereon.

Referring now more particularly to the accompanying drawing wherein like and corresponding parts are designated by similar reference characters throughout the several views, I have herein shown a sectional fuse casing comprising 'an upper section I and a lower section 2 both of which may be molded from glass, porcelain, .bakelite or other suitable insulating materials.

The upper section I has formed therein a central and vertically extending recess 3 forming thelamp compartment of the fuse and communicating with this centrally located recess 3 is a horizontal opening .l in which is adapted to be placed a suitable resisting element. This upper section i of the casing may be provided with suitable serrations 5 whereby the fuse plug may be gripped by the operator for applying the same to and from the socket of the cut-out base .in an electrical wiring system to which it is to be applied. Screw threads 6 are also formed with the outer periphery of the section l adjacent the lower end thereof and projecting centrally from the lower end of the section l is a projection l having a centrally located opening in which is secured a rivet 8.

The lowersection 2 of the casing has formed upon its outer face screw threads 9, a centrally located opening in which the contact rivet I0 is arranged and formed within the upper face of the section 2 is a recess II which forms a fuse compartment.

The indicator preferably employed consists of a miniature glow lamp designated by the numeral I2 which is placed within the lamp compartment 3 of the fuse and is capable of giving a signal from the face of the fuse should the fusible element become blown or ruptured. This lamp has two terminals or lead-in wires, one of which, indicated by the numeral I3, is connected to the rivet 8 secured within the casing`2 and its opposite terminal is electrically connected to one end of the resistor1 herein indicated by the numeral I4 and arranged within the opening 4.of the casing I. The opposite side of this resistor I4 is electrically connected to the upper end of the threaded contact shell I5.

The fusible element comprises avdiscIG made of fiber or other suitable insulating material to which the fuse links are supported and carried. The fuse links are formed from one single piece of zinc having a central portion I'I which extends through and is attached to the central portion of the disc I6 and four branches or links I8 which extend radially from the center of the disc are attached to the outer edges thereof. When a fusible element such as that shown in Figure 4 of the drawing is placed Within the fuse casing, the

Vcentral portion I'I of the saine rests upon the Cil upper end of the contact rivet I 0 and at the same time has electrical connections with the rivet 8 and the wire I3 leading to the glow lamp I2. The disc I6 has four openings I9 formed therein which are at times adapted to register with a circular projection 2B formed with the upper i section I of the casing whereby when the fusible element is inserted within afuse casing, this projection 20 extends within one of the openings I9 and thereby not only holds the fusible element in proper position but prevents the rotation thereof. The projection 'I of the upper section I of the casing is provided with four radially extending wings 2I which contact the upper face of the disc I6 above each link I8. A metal contact strip 22 has one end soldered to or otherwise connected as at 23 to the upper end of the shell I5 and its opposite end 24 extends down within the fuse compartment II so that when a fusible element is inserted within this fuse compartment, one of the contact strips I8 will engage this extended end 24 of the conductor 22. When the fusible element is inserted within the casing of a plug fuse in this manner, one of the fuse links I8 is electrically connected to the two terminals I0 and I5 of the fuse but should such fuse link become blown or ruptured, the disc may be removed and rotated so that one oi the links which remains intact may contact with the conductor Cal 24. In the event all of the fuse links I8 upon one disc I6 become blown and ruptured, the

'entire disc may be discarded and a new one substituted therefor.

The threaded contact shell I5 which engages over the threads 6 formed with the section I of the casing is fastened to this section of the casing by means of the soldered connection 23 and the lower projecting end of this threaded shell l5 is engaged by the threads 9 formed with the lower section of the casing 2 whereby, upon unscrewing the section 2 from this threaded shell, access may be gained to the fusible element arranged therein for replacing the saine when all of the links thereof become blown or ruptured. When replacing a new fusible element, it is only necessary to place a disc I6 containing the fuse links within the fuse compartment until one of the openings IQ of the disc I6 registers with the projection 20 and again placing the section 2 of the casing within the threaded contact shell, the fuse plug is again capable of being re-used.

Manifestly, the construction herein shown is capable of considerable modification and such modifications as come within the scope of my claims, I consider within the spirit of my invention.

1. A renewable plug fuse comprising a casing consisting of an inner and an outer section, a threaded contact shell secured to said outer section and projecting therefrom, screw threads formed with the outer periphery of said inner section and having detachable engagement with the projecting end of said threaded contact shell, a rivet Contact secured to and projecting through said inner section centrally thereof, a disk of insulating material inserted between the sections and formed with openings spaced from each other circumferentially of the disk, a plurality of fuse links secured to said holder and extending radially of the disk from the center thereof in crossing relation tothe openings, each link having its inner end contacting with said rivet, a conductor having one end connected to said threaded contact shell, and a projection carried by said outer section in position to extend through an opening of the disk for preventing rotation of the disk and retaining one of the said fuse links in contact with the opposite end of said conductor.

2. A renewable plug fuse comprising a casing consisting of separable inner and outer sections, the outer section having its inner end formed with a hub and arms extending radially from the hub, a center contact member carried by said inner section, said inner section having an annular recess formed therein in facing relation to the outer section and providing a fusible link compartment between the sections, a disk of nsulating material inserted into said compartment and bearing against the hub and the arms of the outer section, a plurality of fuse links secured to said holder and extending radially thereof from the center of the disk, an opening being formed in the disk opposite each fuse link, a projection carried by the hub of said outer section at the inner end of one of the arms for engaging through one of the openings of the disk to prevent turning of the disk between the sections, a threaded contact shell'for detachably connecting the sections of said casing and holding the sections in clamping engagement with the disk, a conductor member having one end connected to said shell and its opposite end projecting between the sections of said casing and terminating in position for engagingone of the fuse links whereby the fuse link will serve as a. fusible connection between the contact member carried by said inner section and the inner end of said conductor member.

LEROY A. KAUFFMAN. 

